This invention relates to the treatment of web material for example in the manufacture of cardboard boxes.
It has previously been proposed for example in my U.S. Pat. No. 3,756,149, corresponding to British Pat. No. 1,324,169 to provide web treatment apparatus comprising a continuously rotatable rotary member having a part-circumferentially extending web treatment area, a first counter pressure member co-operable with said web treatment area to effect feed of the web therebetween during a part of each revolution of the rotary member, a drive element and a second counter pressure member associated therewith, and variable drive transmission means comprising cam means rotatably fast with said rotary member and a cam follower co-operable with the cam profile of said cam means to transmit rotational drive to said drive element in such a way that, during each revolution of the rotary member, said drive element is accelerated in the same rotational sense as the rotary member immediately prior to feed of the web by said rotary member the first counter pressure member, is decelerated in said same rotational sense immediately subsequent to termination of feed of the web by the rotary member and the first counter pressure member to arrest feed movement of the web, and is accelerated and then decelerated in the opposite rotational sense during the remainder of each revolution of said rotary member to effect reverse feed of the web, the second counter pressure member being co-operable with said drive element during such acceleration and deceleration of the latter to impart feed movement to the web and said cam means comprising a pair of cam parts which are adjustable relative to one another to vary the cam profile.
In such apparatus the web is fed forwardly at the same linear speed as the periphery of the treatment apparatus area, that is the forme of the printer or die-cutter, during the time that the latter co-operates with the said first counter pressure member to effect the printing or die-cutting without slip between the web and forme, and then after the conclusion of that treatment the web is reversed before being fed forwardly again. It is necessary to slow and stop the web before reversing and slow and stop the reverse movement before beginning the forward feed, and to accelerate the web in the forward direction, so that after completion of one cycle the web is again travelling at the correct speed. Moreover, the values of the intermediate steps, between completion of one printing or die-cutting operation and commencement of the next are such, in relation to the other parameters such as the length of the forme, that there is a minimum gap or no gap between such two successive treated areas of the web.
In practice the said apparatus may be used for either printing a web, which is then re-rolled, or for die-cutting to produce a series of cut blanks which are stacked. It has not been possible to effect both printing and die-cutting. The object of the invention is to enable two or more operations such as two-colour printing, or ( and more particularly ) printing and die-cutting to be effected in a single pass through an apparatus.